Technical Abstract:
While aboveground changes in relative plant species and bare ground abundance are commonly used to detect ecosystem response to changes in grazing management, response of belowground properties to management are largely unknown for semi-arid rangelands. Continuous moderate grazing and two different lengths of rest from grazing were used to examine above- and below-ground ecosystem responses to change in management in a northern mixed prairie plant community from 2001 to 2003. The influence of microtopographic position was also measured to evaluate differences between grass-occupied soil and bare ground microsites. One season of rest from grazing significantly increased litter cover, decreased bare ground, and increased cool-season grass species abundance to levels comparable to 8 seasons of rest from grazing. Belowground parameters were less responsive to changes in management. Bulk density decreased in the surface soil with one season of rest from grazing, while root biomass and concentrations of soil C and N were unresponsive to changes in management over the three years of this study, but did respond to year-to-year variations in precipitation. Bare ground microsites had lower root biomass in surface soils and higher temperatures on the soil surface and at 5 cm depth than grass-occupied microsites in all management treatments. Results suggest that aboveground recovery from the disturbance associated with continuous grazing can occur rapidly, and rates of recovery are dependent on annual precipitation levels in this ecosystem.